7β-Arylalkyl-7α-methyl-6-oxo or 6α-hydroxy-3-methoxy or 3-hydroxy-4,5α-epoxy-17-methyl or 17-cycloalkyl-methylmorphinans

ABSTRACT

Disclosed are 7 beta -arylalkyl-7 alpha -methyl-6-oxo or 6 alpha -hydroxy-3-methoxy or 3-hydroxy-4,5 alpha -epoxy-17-methyl or 17-cycloalkylmethyl-morphinans of the formula:   &lt;IMAGE&gt;   wherein R is H or methyl, X is oxo or  alpha -hydroxy, n is 2 to 4 and R1 is methyl, cyclopropylmethyl or cyclobutylmethyl. These compounds are useful as strong analgesics.

BACKGROUND OF THE INVENTION

Morphine is a well-known narcotic analgesic having a structure formula: ##STR2## The compounds of this invention are structurally related to morphine and are named according to the morphinan system of nomenclature using the morphinan nucleus as shown below: ##STR3## The numbering and the stereochemical placement of atoms in the morphinan system is the same as that depicted for morphine. A dashed line is used to represent a covalent bond projecting below the plane of a reference atom while a wedged or heavily accented line signifies a covalent bond above such plane. The compounds of this invention have the same stereochemical placement of atoms as depicted for the morphine nucleus unless otherwise indicated.

In U.S. Pat. No. 4,275,205, there is disclosed 7,7-ditosyloxymethyl-4,5α-epoxy-3-methoxy-17-methyl-morphinan-6.beta.-ols of the formula: ##STR4## where R is H, CH₃ or CH₂ CH₃. These compounds are precursors for certain 7,7-dimethyl-morphinans having analgesic activity or a combination of analgesic and narcotic antagonist activity.

SUMMARY OF THE INVENTION

The present invention involves 3,7-substituted-6-oxo or 6α-hydroxy-4,5α-epoxy morphinans of the formula: ##STR5## wherein R is H or methyl, X is oxo or α-hydroxy, n is 2 to 4 and R₁ is methyl, cyclopropylmethyl or cyclobutylmethyl.

DESCRIPTION OF THE INVENTION

Referring to scheme I, the N-methyl or N-cycloalkylmethyl-6α,7α-oxymethylene compounds A (prepared as described in co-pending application Ser. No. 403,464, filed on July 20, 1982 by Michael P. Kotick, et al) are cleaved to the 6α-hydroxy-7α-methyl compounds B by refluxing with a 3:1 mixture of lithium aluminum hydride-aluminum chloride in ether for 18 hours. The 6α-hydroxy group of B is then oxidized to the ketone (compound C) by use of dimethylsulfoxidetrifluoroacetic anhydride. The 3-methoxy compounds C are converted to 3-hydroxy compounds D using refluxing 48% hydrobromic acid. ##STR6##

The novel morphinan compounds disclosed herein are prepared as described by the following examples where the letter designations correspond with scheme I.

EXAMPLE I 7β-Arylalkyl-17-(cycloalkylmethyl)-4,5α-epoxy-3-methoxy-7α-methylmorphinan-6α-ols (BP, BB)

A suspension of AlCl₃ (1.95 g, 14.6 mmole) in Et₂ O (100 ml) was cooled in an ice bath and LiAlH₄ (1.66 g, 43.9 mmole) added. After stirring for 30 minutes, a solution of 7β-phenylbutyl-17-(cyclopropylmethyl)-4,5α-epoxy-3-methoxy-6.alpha.,7α-(oxymethylene) morphinan (7.1 g, 14.6 mmole) in Et₂ O (250 ml) was added and the mixture refluxed for 18 hours. The cooled mixture was treated sequentially dropwise with H₂ O (1.7 ml), 15% NaOH (1.7 ml) and H₂ O (5.1 ml), then filtered through Celite. The filtrate was diluted with EtOAc and washed with H₂ O. Evaporation gave 5.8 g of a glass which was chromatographed to give 4.43 g (62%) of BPf as a glass. A portion of this material was converted to the HCl salt, which was obtained as white crystals, mp 118°-122° C., from EtOAc. Several recrystallizations from EtOAc gave analytically pure material with an indefinite mp. Anal. (C₃₂ H₄₁ NO₃.HCl). In a similar manner, BBd was obtained as a foam in 84% yield. Crystals of the HCl salt, mp 169°-171° C., were obtained from EtOAc. Anal. (C₃₁ H₃₉ NO₃. HCl). Compound BBf was obtained in 65% yield and crystallized as the HCl salt, mp sinters 116°, melts 123°-130° C. Anal. (C₃₃ H₄₃ NO₃.HCl).

EXAMPLE II 7β-Arylalkyl-17-(cycloalkylmethyl)-4,5α-epoxy-3-methoxy-7α-methylmorphinan-6-one (CP, CB)

To a solution of dimethylsulfoxide (1.0 ml, 14.3 mmole) in methylene chloride (CH₂ Cl₂) under argon at -60° C., was added dropwise, trifluoroacetic anhydride (1.5 ml, 10.7 mmole) in CH₂ Cl₂ (7 ml). After 10 minutes, a solution of BPf (3.48 g, 7.1 mmole) in CH₂ Cl₂ (50 ml) was added slowly. The mixture was kept at -60° C. for 90 minutes, then triethylamine (3 ml) was added and the mixture warmed to room temperature. After washing with H₂ O, evaporation of the organic phase gave 3.47 g of CPf as a foam. The HCl salt, mp 105°-110° C., was recrystallized several times from EtOAc and best analyzed as containing 0.33 mmole EtOAc. Anal. (C₃₂ H₃₉ NO₃.HCl.0.33 EtOAc). The free base of CBc was obtained as crystals, mp 150°-151° C., in 77% yield after chromatography and crystallization from EtOAc-Et₂ O. Anal. (C₃₁ H₃₇ NO₃). Compound CBf was obtained in quantitative yield as crystals, mp 149°-152° C. Recrystallization from EtOAc gave 96% yield of pure CBf, mp 150°-151.5° C. Anal. (C₃₃ H₄₁ NO₃) C, H, N.

EXAMPLE III 7β-Arylalkyl-17-(cycloalkylmethyl)-4,5α-epoxy-3-hydroxy-7α-methyl-morphinan-6-ones (DP, B)

A mixture of the appropriate compound C from example II and 48% HBr was refluxed for 15 minutes, the mixture cooled and diluted with H₂ O. The solution was made basic by the addition of NH₄ OH and extracted with chloroform (CHCl₃). Evaporation was followed by chromatography of the residue. Chromatography gave DBf in 63% yield as a foam. Crystals of DPf, mp 183.5°-185° C., were deposited from EtOAc. Anal. (C₃₁ H₃₇ NO₃). Compound DBc was obtained in 42% yield after chromatography. The HCl salt, mp sinters above 200° C., crystallized from EtOAc. Anal. (C₃₀ H₃₅ NO₃.HCl). The foam obtained upon workup of DBf crystallized upon titration with EtOAc. These crystals, obtained in 53% yield, were recrystallized from EtOAc to give pure DBf, mp 186°-188.5° C. Anal. (C₃₂ H₃₉ NO₃).

    ______________________________________                                         ELEMENTAL ANALYSES                                                             Com-                                                                           pound Formula           % C    % H  % N                                        ______________________________________                                         BPf   C.sub.32 H.sub.41 NO.sub.3.HCl                                                                   73.33  8.08 2.67 Calc.                                                         73.22  8.20 2.61 Found                                 BBd   C.sub.31 H.sub.39 NO.sub.3.HCl                                                                   72.99  7.90 2.75                                                               73.06  8.09 2.83                                       BBf   C.sub.33 H.sub.43 NO.sub.3.HCl                                                                   73.65  8.24 2.60                                                               73.56  8.21 2.52                                       CPf   C.sub.32 H.sub.39 NO.sub.3.HCl.0.33 EtOAc                                                        72.60  7.80 2.54                                                               72.43  7.44 2.68                                       CBd   C.sub.31 H.sub.37 NO.sub.3                                                                       78.94  7.91 2.97                                                               78.95  8.08 2.81                                       CBf   C.sub.33 H.sub.41 NO.sub.3                                                                       79.32  8.27 2.80                                                               79.45  8.15 2.67                                       DPf   C.sub.31 H.sub.37 NO.sub.3                                                                       78.95  7.91 2.97                                                               78.89  7.89 2.69                                       DBd   C.sub.30 H.sub.35 NO.sub.3.HCl                                                                   72.93  7.34 2.84                                                               73.21  7.59 2.63                                       DBf   C.sub.32 H.sub.39 NO.sub.3                                                                       79.14  8.09 2.88                                                               79.17  8.11 2.72                                       ______________________________________                                    

EXAMPLE IV 7α,17-Dimethyl-4,5α-epoxy-3-methoxy-7β-(4-phenylbutyl)morphinan-6α-ol (BMf)

To a suspension of AlCl₃ (1.29 g, 9.6 mmole) in Et₂ O (100 ml) under argon, cooled in an ice bath, was added LiAlH₄ (1.10 g, 28.9 mmole). The mixture was stirred for 30 min. in the bath after which a solution of 4,5α-epoxy-3-methoxy-17-methyl-7β-(4-phenylbutyl)-6α,7.alpha.-(oxymethylene)morphinan (4.20 g, 9.4 mmole) in Et₂ O (200 ml) was added. The mixture was then refluxed for 2 days. The reaction mixture was quenched by the addition of H₂ O and 3 N NaOH. After filtration from insoluble material, the filtrate was evaporated and the residue diluted with H₂ O and extracted with EtOAc. Processing in the usual fashion followed by chromatography gave 2.41 g (57%) of BMf as a glass. Crystallization of a portion of this material from EtOAc-hexane gave crystals, mp 90°-93° C. Drying at 35° C. in high vacuum gave crystals with mp 89°-92° C. which were shown by NMR to be the 0.25 solvate of BMf with hexane: NMR δ 7.22 (s, 5H, phenyl); 6.63 (s, 2H, H1 and H2); 4.72 (d, 1H, H5, J=5 Hz); 3.85 (CH₃ O--); 3.62 (d, 1H, H6); 0.87 (s, 7α CH₃ --).

Anal. Calcd. for C₂₉ H₃₇ NO₃.0.25 C₆ H₁₄ : C, 78.08; H, 8.70; N, 2.99. Found: C, 77.75; H, 9.04; N, 2.99.

EXAMPLE V 7α,17-Dimethyl-4,5α-epoxy-3-methoxy-7β-(4-phenylbutyl)morphinan-6-one (CMf)

A mixture of DMSO (9.6 mmole) and TFAA (7.2 mmole) in CH₂ Cl₂ (15 ml) was prepared as above at -60° C. To this was added BMf (2.14 g, 4.78 mmole) in CH₂ Cl₂ (70 ml) and the reaction conducted in the usual fashion for 90 min. After the addition of TEA (2 ml) and processing in the usual manner, chromatography gave 1.79 g (84%) of CMf as a glass: NMR δ 7.18 (broad, s, 5H); 6.61 (s, 2H); 4.76 (s, 1H, H5); 3.92 (CH₃ O--); 2.43 (CH₃ N--); 0.88 (s, 3H, 7α CH₃ --). A portion of this material was converted to the HCl salt which gave crystals, mp 224°-226° C., from EtOAc.

Anal. Calcd. for C₂₉ H₃₅ NO₃.HCl: C, 72.26; H, 7.53; N, 2.90. Found: C, 71.86; H, 7.51; N, 2.74.

EXAMPLE VI 7α,17-Dimethyl-4,5α-epoxy-3-hydroxy-7β-(4-phenylbutyl)morphinan-6-one (DMf)

A solution of CMf.HCl (1.43 g, 2.97 mmole) in CHCl₃ (60 ml) was added to a solution of BBr₃ (1.82 ml, 19.2 mmole) in CHCl₃ (40 ml) cooled in an ice bath under argon. The mixture was stirred for 30 min. at ambient temperature, then recooled to 0° C. and MeOH (5 ml) added dropwise. The resulting mixture was evaporated, the residue dissolved in H₂ O and excess concentrated NH₄ OH added. Processing with CHCl₃ gave 1.30 g of a foam which was chromatographed to give 0.87 g of recovered CMf followed by 0.50 g (39%) of DMf as a glass: NMR δ 4.70 (s, H5); 2.46 (CH₃ N--); 0.88 (s, 7α CH₃ --). This was converted to the HCl salt which crystallized from MeOH-EtOAc to give 22.HCl, mp >265° C.

Anal. Calcd. for C, 71.86; H, 7.32; N, 2.99. Found: C, 71.46; H, 7.16; N, 2.80.

PHARMACOLOGICAL EVALUATION

Analgesic effects of the test compounds were determined in mice by use of the acetic acid induced writhing test described by B. A. Whittle, Brit. J. Pharmacol., 22:246 (1964). In this test, at least 3 groups of 5 male CD-1 mice each were given subcutaneous doses of the test drug dissolved in distilled water. In all cases, 0.4 ml of a 0.5% v/v acetic acid in distilled water solution was administered intraperitoneally 15 min. post drug. The number of writhes in a 20 min. interval beginning 5 min. after the acetic acid injection were determined and compared with the number of writhes in a control group which had received only acetic acid.

Percent inhibition of writhing was calculated as: ##EQU1##

The ED₅₀ dose, i.e., the dose required to reduce the number of writhes by 50%, was determined graphically from a plot of % inhibition as a probit verus log dose. Confidence limits of 95% were calculated on the basis of those results falling in the range 16-84% inhibition. See Lichtfield, J. T. and Wilcoxon, F., J. Pharmacol. Exp. Ther., 96, 99-113 (1949).

The results of this evaluation are set out in table I.

                  TABLE I                                                          ______________________________________                                          ##STR7##                                                                                                       ED.sub.50                                                                               ED.sub.50                            Compound                                                                               R       R.sub.1                                                                              N    X     (μmole/kg)                                                                           (mg/kg)                              ______________________________________                                         BPf.sup.a                                                                              CH.sub.3                                                                               P     4     OH   0.50     0.26                                 BBd.sup.a                                                                              CH.sub.3                                                                               B     2     OH   1.0      0.51                                 BBf.sup.a                                                                              CH.sub.3                                                                               B     4     OH   11.3     6.1                                  CPf     CH.sub.3                                                                               P     4    O     2.0      1.1                                  CBd.sup.b                                                                              CH.sub.3                                                                               B     2    O     0.01     0.011                                CBf     CH.sub.3                                                                               B     4    O     5.6      2.8                                  DPf     H       P     4    O     0.11     0.07                                 DBd     H       B     2    O     0.04     0.021                                DBf     H       B     4    O     0.17     0.08                                 BMf     CH.sub.3                                                                               M     4     OH   0.049    0.023                                CMf.sup.a                                                                              CH.sub.3                                                                               M     4    O     0.023    0.011                                DMf.sup.a                                                                              H       M     4    O     0.010    0.0048                               ______________________________________                                          .sup.a HCl salt                                                                .sup.b d-tartrate salt                                                         B = cyclobutylmethyl                                                           P = cyclopropylmethyl                                                          M = methyl                                                               

The compounds claimed herein, especially those with small ED₅₀ values, are very potent narcotic agonists. As such, they are useful for the relief of pain, for pre-operative anesthesia or for the immobilization of large animals. The dose to be administered to achieve the desired result, i.e., the effective dose, may vary from individual to individual but is readily determined by one skilled in the art without undue experimentation.

The compounds of the present invention form pharmacologically active addition salts with organic acids. Typical acid addition salts are the tartrate and maleate. These compounds may be administered by known conventional methods such as intravenous, parenteral, buccal, rectal or oral routes. Dose forms for the administration of these compounds can be prepared by methods recognized in the pharmaceutical sciences. 

What is claimed is:
 1. 7β-arylalkyl-7α-methyl-6-oxo or 6α-hydroxy-3-methoxy or 3-hydroxy-4,5α-epoxy-17-methyl or 17-cycloalkylmethyl-morphinans of the formula: ##STR8## wherein R is H or methyl, X is oxo or α-hydroxy, n is 2 to 4 and R₁ is methyl, cyclopropylmethyl or cyclobutylmethyl.
 2. A compound as defined by claim 1 wherein R is methyl, X is α-hydroxy, n is 4 and R₁ is cyclopropylmethyl.
 3. A compound as defined in claim 1 wherein R is methyl, X is α-hydroxy, n is 2 and R₁ is cyclobutylmethyl.
 4. A compound as defined by claim 1 wherein R is methyl, X is oxo, n is 2 and R₁ is cyclobutylmethyl.
 5. A compound as defined by claim 1 wherein R is H, X is oxo, n is 4 and R₁ is cyclopropylmethyl.
 6. A compound as defined by claim 1 wherein R is H, X is oxo, n is 2 and R₁ is cyclobutylmethyl.
 7. A compound as defined by claim 1 wherein R is H, X is oxo, n is 4 and R₁ is cyclobutylmethyl.
 8. A compound as defined by claim 1 wherein R is methyl, X is α-hydroxy, n is 4 and R₁ is methyl.
 9. A compound as defined by claim 1 wherein R is methyl, X is oxo, n is 4 and R₁ is methyl.
 10. A compound as defined by claim 1 wherein R is H, X is oxo, n is 4 and R₁ is methyl. 